Abstract Objective. cat eye syndrome is considered a rare chromosome disease with a highly variable phenotype. the objective of this paper was to describe the clinical characteristics of a sample of patients with cat eye syndrome who were seen at our service. Methods. this is a retrospective analysis of a sample of six patients with diagnoses of cat eye syndrome. all of these patients’ karyotypes exhibited the presence of an additional marker chromosome, inv dup(22)(pter->q11.2::q11.2->pter). one patient also exhibited mosaicism with a lineage that had a normal chromosomal constitution. clinical and follow-up data were collected from the patients’ medical records. fisher’s exact test was used to compare the frequencies observed in our study with figures given in the literature (Pq11.2::q11.2->pter). This, as its description states, involves duplication of the entire short arm of chromosome 22 (p) plus

part of its long arm (q), as far as band 11. It is now known that this band contains regions of low copy repeats (LCRs) which predispose it to rearrangements, including the marker chromosome observed in cat eye syndrome (Heather et al., 2002). Clinically, the disease is characterized by the presence of multiple malformations, primarily involving the eyes, ears and anorectal and urogenital systems. Notwithstanding, the phenotype that has been observed is highly variable and includes descriptions of very mild cases (Berends et al., 2001; Rosias et al., 2001). Therefore, in response to the scarcity of studies of the disease

in Brazil (Belangero et al., 2009), the objective of this paper is to describe the clinical characteristics of a sample of patients with cat eye syndrome who were seen at our service.

Methods This is a retrospective analysis of a sample of six patients with diagnoses of cat eye syndrome who were referred to the Clinical Genetics Department because of anal atresia, preauricular tags and/or preauricular pits, associated with other malformations. All of these patients’ karyotypes exhibited the presence of an additional marker chromosome, similar to the dicentric chromosome found in the partial tetrasomy 22: inv dup(22)(pter>q11.2::q11.2->pter) (see Figure 1). One patient also exhibited mosaicism with a lineage that had a normal chromosomal constitution: 47,XX, inv dup(22)(pter-->q11.2::q11.2->pter) [30]/ 46,XX[14]. In three cases it was possible to karyotype the patients’ mothers and in one case the father was karyotyped, with normal results in all four cases. The following data were collected from patient records: age and sex, referring service, anthropometric measurements, parents’ age at birth of patient, clinical characteristics observed on physical examination, results of supplementary tests and